The invention relates generally to multi-terminal or multi-contact electrical connectors to connect electrical contacts of various shapes. The invention relates more specifically to electrical connectors of the insulation piercing, gas tight electrical connection type to quickly and inexpensively interconnect a wide variety of contacts to conventional flexible circuit, tape cable or encapsulated round wire harness. Most specifically the invention relates to an electrical connector that terminates more than twice the number of contacts per inch than a conventional insulation displacing connector and eliminates the expense of soldering, crimping or welding usually associated with the attachment of a connector contact to an interconnect circuit.
Conventional electrical connectors are designed to connect the circuit paths of a flexible circuit to a spring contact system. Usually the surface of the flexible circuit needs to be prepared before connection. Preparation of a flexible circuit usually includes labor intensive activities such as stripping off the dielectric, cleaning the exposed conductor or wire and then soldering each individual conductor of the spring contact system to each conductor or wire of the flexible circuit. As part of the reason many connectors require intensive preparation of the flexible circuit, many conventional connectors do not provide a wiping action to clean the conductors of the flexible circuit. Some connectors also do not provide a gas tight seal when the electrical connection is made, allowing air to contact the conductors causing oxidation, and consequent degradation in the quality of the connection due to the oxidation on the conductors.
Many conventional multi-terminal connectors comprise male and female housings that fasten together to secure coupling of terminals mounted within the housings. Many connectors require a fair amount of force to completely engage the many terminals being connected. Zero insertion force type connectors aim at reducing or eliminating the force typically needed to make the connection. In reducing the force, some connector systems use camming devices or cam lock features. Cam lock features typically include one or more cam surfaces on an operator handle or lever that is mounted to the housing of one of the connector halves to be mated. The other connector housing has one or more protruding cam followers to engage the cam surface(s) so that as the lever or handle is moved in the desired direction, the cam surface(s) act on the cam follower(s), drawing the connector halves together and forcing secure engagement of the contacts.
Other zero insertion force type connectors conventionally have a housing mounting a plurality of terminals in a generally parallel array. An actuator, such as a pressure member, is used to press the flexible flat cable, flexible printed circuit board or the like against contact portions of the terminals. In order to keep the size of the connectors relatively small, and the insertion force required to connect the terminals to a minimum, some connectors have been designed with actuators or pressure members which are rotatably or pivotally mounted on the housing for movement between first, open positions allowing free insertion of the cables into the connector housings, and second, closed positions for clamping the flat cables against the contact portions of the terminals.
One of the problems with connectors having rotatable actuators, cams or pressure members is the tendency of moving the pressure member back toward its open position when undesired external forces are applied to the flexible flat cable. The flexible flat cable tends to raise and rotate the pressure member, thereby releasing the flexible flat cable from the connector, and possibly damaging the terminals in the process of the flexible flat cable being pulled out of or disconnected from the connector.
Thus there is a need for an inexpensive, easily assembled connector that eliminates the expensive, time consuming preparation steps common to use of most connectors, and that eliminates strain on the electrical connection or inadvertent disconnection, by securely locking the flexible flat cable, flexible printed circuit board, round wire interconnect or the like in place within the connect, while producing a gas tight seal.
The basic embodiment of the invention is a connector that accurately aligns each contact to its assigned conductor. Individual contacts of at least one contact or at least one compound dynamic contact gradually engage the conductive circuit (flat flexible cable, flexible printed circuit board, round wire interconnect) and apply sufficient force to pierce, via a tapered insulation plane on each contact, through the circuit""s dielectric but not its individual conductors. The contact(s) are deflected, in a first deflection range, by the circuit""s conductor in such a way as to skive off (remove, peel off) all the insulating dielectric and a majority of the adhesive on one side of the conductive circuit without totally piercing the conductor.
In one embodiment, may be a rotatable cam or cylinder into which the circuit passes. A portion of the circuit is retained in the cam. The circuit may enter partially or pass all the way through the cam. As the cam or cylinder rotates through its rotation cycle, the conductive circuit is wrapped around it, and the cam or cylinder includes raised features designed to lift at least one conductor of a flexible circuit into an electrical connection with a deflectable contact and to then lift the deflectable contact into a second deflection range. The contact(s), as it is deflected into the second deflection range, moves the contact""s insulation plane into a neutral (non-cutting) position and significantly increases the contact force on the circuit""s conductor.
This sequence of mechanical events brings the optional force concentrators on the contact(s) into a high pressure connection with the conductive circuit""s conductors. The contact is designed to apply sufficient pressure between each contact and its mating conductor to pierce through any remaining adhesive and make a metal to metal, or surface finish to surface finish gas-tight electrical connection. In another embodiment, there may be a contact module containing at least one compound dynamic contact, but with a contact activation portion instead of a cam. In either embodiment, a simple contact having an insulation plane pierces and peels back the top layer of dielectric from a flexible conductive circuit such that a partial seal is formed between each contact and the individual conductors of the flexible conductive circuit.
Therefore an aspect of invention is to provide an interconnect system to quickly and inexpensively interconnect a wide variety of shapes of contacts to conventional conductive circuits such as flexible circuit, tape cable, or encapsulated round wire harness.
Another aspect of the invention is to provide an interface within the connector""s body wherein the connector is adaptable to an application specific contact shape exiting the connector body. Exiting contacts may be designed as a simple pin for insertion into a printed circuit board or a complex spring designed to mate with other connectors.
A further aspect of the invention is to provide a connector that eliminates the expense of removing the insulation and cleaning the conductors of the flexible circuit and soldering, crimping or welding that is usually associated with the attachment of a connector contact to an interconnect circuit.
Yet another aspect is to provide a sealing mechanism wherein the displaced dielectric and adhesive of the conductive circuit are compressed against the side walls of the connector housing providing a partial contact to conductor seal. The seal can be easily made permanent by heating each circuit conductor to a temperature that causes the dielectric to flow and thereby seal the contact to conductor interface.
A still further aspect is to provide a connector that only pierces through the upper layer of a conductive circuit""s dielectric, leaving the base laminate layer intact. By eliminating the need to remove or penetrate the base layer of dielectric, the conductive circuit""s dimensional stability is maintained and tearing or damaging the conductive circuit is avoided. Also any risk of changing the conductive circuit""s electrical or dielectric parameters is avoided.
A further aspect of the invention is to provide a connector that can be mounted to the end of a flexible conductive circuit without first removing the dielectric from the terminating area, that can be mounted without the use of tooling, and that can be easily coupled to a mating connector with minimal hand movements and without having to observe the connection site.
Still another aspect is to provide a connector that is relatively easy and inexpensive to make in quantity.
Still another aspect is to provide a connector that configures the flexible circuit in a manner that strain relieves the circuit and in so doing protects the contact to conductor electrical interface.
Still another aspect is to provide a low pressure contact system that may be used in those applications requiring a gold to gold interface or a ZIF (zero insertion force) style connector. In this type of application the flexible circuits insulating overlay must be first removed from the circuit before it is inserted into the connector.
Other aspects of the invention will be exemplified by the following drawing figures, detailed description of the preferred embodiments of the invention, and the appended claims.